feat: add Docker healthchecks, remove Uptime Kuma

- Add healthcheck configurations to 13 stacks for Portainer status monitoring
- Remove Uptime Kuma service (replaced by Docker healthchecks)
- Clean up stale Heimdall references
- Update documentation and service counts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

stacks/netdata.yml

@@ -27,6 +27,12 @@ services:
       # Optional: Claim to Netdata Cloud for remote access
       # - NETDATA_CLAIM_TOKEN=your-claim-token
       # - NETDATA_CLAIM_URL=https://app.netdata.cloud
+    healthcheck:
+      test: ["CMD-SHELL", "curl -fSs http://localhost:19999/api/v1/info || exit 1"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 30s
     networks:
       - docker-dataplane